Doubtful Sound, Fjordland, New Zealand - named by Captain Cook, has he was unsure that he could navigate it by sail - and he worried that if he entered, he might not get back out. It was also visited by Alessandro Malaspina in 1793. ..There's two layers of water in Doubtful Sound - fresh water from the mountains on top, and saline water from the sea underneath. An abundance of deep sea life can survive here, even in these shallow waters, including black coral.